I want to realize the matrix multiplication using Strassen method. Since my input matrix will not be 2^n *2^n all the time, for example, it could be 3*3 matrix, I need to fill the edge area with 0. But I came across a problem when I create new matrix A_new[][] for A[][], B_new[][] for B[][]. I can successfully generate the A_new[][] and B_new[][] for both square(2*2, etc.) or (3*3,etc.). But when I want to further use A_new[][] and B_new[][], which I created before, the code outside the "if" statement couldn't see it.
Is there some ways that I could make the code which is outside the "if" statement see it and process it?
Here are my code.
void strassen(int A[][N], int B[][N], int C[][N]) {
if (N == 1) {
C[0][0] = A[0][0] * B[0][0];
}
if (N > 1 && N % 2 != 0) {
int A_new[N + 1][N + 1];
int B_new[N + 1][N + 1];
int i, j;
for (i = 0; i < N + 1; i++) {
if (i == N) {
for (j = 0; j < N + 1; j++) {
A_new[i][j] = 0;
B_new[i][j] = 0;
}
} else {
for (j = 0; j < N + 1; j++) {
if (j == N) {
A_new[i][j] = 0;
B_new[i][j] = 0;
} else {
A_new[i][j] = A[i][j];
B_new[i][j] = B[i][j];
}
}
}
}
for (i = 0; i < N + 1; i++) {
for (j = 0; j < N + 1; j++) {
C[i][j] = 0;
}
}
} else {
int i, j;
int A_new[N][N];
int B_new[N][N];
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
A_new[i][j] = A[i][j];
}
}
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
B_new[i][j] = B[i][j];
}
}
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
C[i][j] = 0;
}
}
}
if you move int A_new[N + 1][N + 1]; and int B_new[N + 1][N + 1]; before the if you can use A and B in the two branches of the if without problem, and they are available after the if too of course. You do not use all the cells in the else branch but that has no consequences
int A_new[N + 1][N + 1];
int B_new[N + 1][N + 1];
if (N > 1 && N % 2 != 0) {
int i, j;
for (i = 0; i < N + 1; i++) {
if (i == N) {
for (j = 0; j < N + 1; j++) {
A_new[i][j] = 0;
B_new[i][j] = 0;
}
} else {
for (j = 0; j < N + 1; j++) {
if (j == N) {
A_new[i][j] = 0;
B_new[i][j] = 0;
} else {
A_new[i][j] = A[i][j];
B_new[i][j] = B[i][j];
}
}
}
}
for (i = 0; i < N + 1; i++) {
for (j = 0; j < N + 1; j++) {
C[i][j] = 0;
}
}
} else {
int i, j;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
A_new[i][j] = A[i][j];
}
}
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
B_new[i][j] = B[i][j];
}
}
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
C[i][j] = 0;
}
}
}
As chux says in a remark you missed an else (or you just return if N == 1 ?) and the code can be
int A_new[N + 1][N + 1];
int B_new[N + 1][N + 1];
if (N == 1) {
C[0][0] = A[0][0] * B[0][0];
}
else if (N > 1 && N % 2 != 0) {
int i, j;
for (i = 0; i < N + 1; i++) {
if (i == N) {
for (j = 0; j < N + 1; j++) {
A_new[i][j] = 0;
B_new[i][j] = 0;
}
} else {
for (j = 0; j < N + 1; j++) {
if (j == N) {
A_new[i][j] = 0;
B_new[i][j] = 0;
} else {
A_new[i][j] = A[i][j];
B_new[i][j] = B[i][j];
}
}
}
}
for (i = 0; i < N + 1; i++) {
for (j = 0; j < N + 1; j++) {
C[i][j] = 0;
}
}
} else {
int i, j;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
A_new[i][j] = A[i][j];
}
}
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
B_new[i][j] = B[i][j];
}
}
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
C[i][j] = 0;
}
}
}
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This code is a program that will move the index position of several names according to the size of the toga that each participant has, and according to the name that the user wants to change.
#include <stdio.h>
#include <string.h>
typedef struct
{
char nama[100];
char ukuran[100];
} toga;
int main()
{
int n, m;
scanf("%d%d", &n, &m);
toga matriks[n][m];
int jumlah[n][m];
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
scanf("%s%s", &matriks[i][j].nama, &matriks[i][j].ukuran);
if(strcmp(matriks[i][j].ukuran, "XS") == 0)
{
jumlah[i][j] = 32;
}
else if(strcmp(matriks[i][j].ukuran, "S") == 0)
{
jumlah[i][j] = 36;
}
else if(strcmp(matriks[i][j].ukuran, "M") == 0)
{
jumlah[i][j] = 37;
}
else if(strcmp(matriks[i][j].ukuran, "L") == 0)
{
jumlah[i][j] = 38;
}
else if(strcmp(matriks[i][j].ukuran, "XL") == 0)
{
jumlah[i][j] = 40;
}
else if(strcmp(matriks[i][j].ukuran, "XXL") == 0)
{
jumlah[i][j] = 42;
}
else if(strcmp(matriks[i][j].ukuran, "XXXL") == 0)
{
jumlah[i][j] = 45;
}
}
}
maybe this part is the problem?
toga ditukar1[50][50];
toga ditukar2[50][50];
int cek2 = 0;
for (int i = 0; i < 50; i++)
{
for(int j = 0; j < 1; j++)
{
scanf("%s", &ditukar1[i][0].nama);
if(strcmp(ditukar1[i][0].nama, "Selesai") == 0)
{
j = 1;
i = 50;
}
else
{
scanf("%s ", &ditukar1[i][1].nama);
// cek1++;
}
}
cek2++;
}
cek2 -= 1;
// printf("ini cek1 : %d\n", cek1);
// printf("ini cek2 : %d\n", cek2);
toga matriks_baru[m][n];
for (int i = 0, a = 0; i < m && a < m; i++, a++)
{
for (int j = 0, b = 0; j < n && b < n; j++, b++)
{
strcpy(matriks_baru[a][b].nama ,matriks[j][i].nama);
}
}
int max_len[m];
max_len[0] = 0;
int terpanjang[m];
int a = 0;
for (int i = 0; i < m; i++)
{
max_len[a] = 0;
for (int j = 0; j < n; j++)
{
if(strlen(matriks_baru[i][j].nama) > max_len[a])
{
max_len[a] = strlen(matriks_baru[i][j].nama);
}
}
a++;
}
printf("Posisi awal :\n");
for(int i = 0; i < n; i++)
{
a = 0;
for(int j = 0; j < m; j++)
{
if(j != m-1)
{
printf("%s ", matriks[i][j].nama);
}
else
{
printf("%s", matriks[i][j].nama);
}
if(j != m-1)
{
for(int k = 0; k < (max_len[a]) - (strlen(matriks[i][j].nama)); k++)
{
printf(" ");
}
}
a++;
}
printf("\n");
}
printf("\n");
int baris1, baris2;
int kolom1, kolom2;
int k = 0;
int l = 0;
maybe this part is the problem?
here I will check whether the name entered by the user whose index you want to exchange is in the matrix
for(int l = 0; l < cek2; l++)
{
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
{
for(int a = 0; a < n; a++)
{
for(int b = 0; b < m; b++)
{
if(strcmp(ditukar1[l][0].nama, matriks[i][j].nama) == 0)
{
baris1 = i;
kolom1 = j;
if(strcmp(ditukar1[l][1].nama, matriks[a][b].nama) == 0)
{
// printf("%d\n", l);
baris2 = a;
kolom2 = b;
if(baris1 < baris2)
{
char temp1[] = "0";
int temp2 = 0;
if(jumlah[baris1][kolom1] > jumlah[baris2][kolom2])
{
temp2 = jumlah[baris1][kolom1];
jumlah[baris1][kolom1] = jumlah[baris2][kolom2];
jumlah[baris2][kolom2] = temp2;
strcpy(temp1, matriks[baris2][kolom2].nama);
strcpy(matriks[baris2][kolom2].nama, matriks[baris1][kolom1].nama);
strcpy(matriks[baris1][kolom1].nama, temp1);
}
}
else if(baris1 > baris2)
{
char temp1[] = "0";
int temp2 = 0;
if(jumlah[baris2][kolom2] > jumlah[baris1][kolom1])
{
temp2 = jumlah[baris2][kolom2];
jumlah[baris2][kolom2] = jumlah[baris1][kolom1];
jumlah[baris1][kolom1] = temp2;
strcpy(temp1, matriks[baris1][kolom1].nama);
strcpy(matriks[baris1][kolom1].nama, matriks[baris2][kolom2].nama);
strcpy(matriks[baris2][kolom2].nama, temp1);
}
}
}
}
}
}
}
}
}
for (int i = 0, a= 0; i < m && a < m; i++, a++)
{
for (int j = 0, b = 0; j < n && b < n; j++, b++)
{
strcpy(matriks_baru[a][b].nama ,matriks[j][i].nama);
}
}
int max_len2[m];
max_len2[0] = 0;
int s = 0;
for (int i = 0; i < m; i++)
{
max_len2[s] = 0;
for (int j = 0; j < n; j++)
{
if(strlen(matriks_baru[i][j].nama) > max_len2[s])
{
max_len2[s] = strlen(matriks_baru[i][j].nama);
}
}
s++;
}
printf("Posisi akhir :\n");
for(int i = 0; i < n; i++)
{
s = 0;
for(int j = 0; j < m; j++)
{
if(j != m-1)
{
printf("%s ", matriks[i][j].nama);
}
else
{
printf("%s", matriks[i][j].nama);
}
if(j != m-1)
{
for(int k = 0; k < (max_len2[s]) - (strlen(matriks[i][j].nama)); k++)
{
printf(" ");
}
}
s++;
}printf("\n");
}
return 0;
}
int szar(t_obraz obr)
{
int x = 0, i, j;
int **wsp;
wsp = (int **)malloc(obr.wymy * sizeof(int *));
for (i = 0; i < obr.wymy; i++)
{
wsp[i] = (int *)malloc(obr.wymx * sizeof(int));
}
for (i = 0; i < obr.wymy; i++)
{
for (j = 1; j < 3 * obr.wymx; j += 3)
{
wsp[i][x] = (obr.obraz[i][j - 1] + obr.obraz[i][j] + obr.obraz[i][j + 1]) / 3;
x++;
}
}
for (i = 0; i < obr.wymy; i++)
{
obr.obraz[i] = (int *)realloc(obr.obraz[i], obr.wymx * sizeof(int));
}
for (i = 0; i < obr.wymy; i++)
{
for (j = 0; j < obr.wymx; j++)
{
obr.obraz[i][j] = wsp[i][j];
}
}
for (i = 0; i < obr.wymy; i++)
{
free(wsp[i]);
}
free(wsp);
}
I have segmentation fault(core dumped), when try to compile that. I have array obraz[wymy][3*wymx] in structure t_obraz.
I think you need to reset your x in the outer Loop
for (i=0;i<obr.wymy;i++) {
x = 0; // here
for (j=1;j<3*obr.wymx;j+=3) {
wsp[i][x]=(obr.obraz[i][j-1]+obr.obraz[i][j]+obr.obraz[i][j+1])/3;
x++;
}
}
In C program which find union and intersection of two input arrays, I have a problem in intersection part. The problem is when I print out the intersection array I[u + z], the output is only one number repeated, without printing other intersections of the two arrays.the part of code has the problem is at the end of the code.
#include <stdio.h>
#include <stdlib.h>
int main()
{
int n, z, f ;
printf("Enter size of array\n");
scanf("%d", &n);
int a[n];
if(n <= 20) {
for(int i = 0 ; i < n; i++) {
printf("Enter integer \n");
scanf("%d", &a[i]);
}
}
for(int i = 0 ; i < n; i++) {
printf("%d " ,a[i]);
}
printf("\nEnter size of the 2nd array\n");
scanf("%d", &z);
int b[z];
if(z <= 20 ){
for(int i = 0 ; i < z; i++) {
printf("Enter integer \n");
scanf("%d", &b[i]);
}
}
for(int i = 0 ; i < z; i++) {
printf("%d " ,b[i]);
}
for(int i = 0 ; i < n; i++) {
for(int j = i + 1; j < n; j++) {
if(a[i] == a[j]) {
for(int l = j; l < n; l++)
{
a[l] = a[l + 1];
}
n--;
j--;
}
}
}
printf("\nArray1: ");
for(int i = 0 ; i < n; i++) {
printf("%d ", a[i]);
}
for(int t = 0; t < z; t++) {
for(int u = t + 1; u < z; u++) {
if(b[t] == b[u]) {
for(int l = u; l < z; l++)
{
b[l] = b[l + 1];
}
z--;
u--;
}
}
}
printf("\nArray2: ");
for(int e = 0; e < z; e++) {
printf("%d ", b[e]);
}
int u[n + z] ; //union
for(int i = 0; i < n; i++) {
u[i] = a[i];
}
for(int i = n ; i < n + z; i++) {
u[i] = b[i - n];
}
for(int i = n ; i < n + z; i++) { //remove repeated values from union
for(int j = i + 1; j < n + z; j++) {
if(u[i] == u[j]) {
for(int l = j; l < n + z; l++)
{
u[l] = u[l + 1];
}
n + z--;
j--;
}
}
}
printf("\n union is ");
for(int i = n ; i < n + z; i++) {
printf("%d ",u[i]);
}
// to get intersection
int I[n + z]; // to get intersection
for(int i = 0; i < n; i++) {
for(int j = 0; j < z; j++) {
if(a[i] == b[j]) {
for(int k = 0; k < n + z; k++) {
I[k] = a[i];
}
}
}
}
printf("\n intersection is ");
for(int i = 0; i < n + z; i++) {
printf("%d ", I[i]);
}
return 0;
}
You should add only one number when you find equality, not for the whole array.
// to get intersection
int I[n + z];
k = 0;
for(int i = 0; i < n; i++)
for(int j = 0; j < z; j++)
if(a[i] == b[j]) {
I[k++] = a[i];
break;
}
printf("\n intersection is ");
for(int i = 0; i < k; i++)
printf("%d ", I[i]);
#include <stdio.h>
int main() {
int a, b, A[100], B[100], I[100], i, j, k = 0, l; /* i have also taken
intersection array. as I[100] */
printf("pls enter the a and b respectively ..\n");
scanf("%d%d", & a, & b);
printf("pls enter the elements in A\n");
for (i = 0; i < a; i++) {
scanf("%d", & A[i]);
}
printf("pls enter the elements in B\n");
for (i = 0; i < b; i++) {
scanf("%d", & B[i]);
}
// intersection calculation
printf("intersection =");
printf("{");
for (i = 0, k = 0; i < a; i++) {
for (j = 0; j < b; j++) {
if (A[i] == B[j]) {
printf("%d,", A[i]);
I[k] = A[i];
k++;
}
}
}
printf("}\n");
// lets find union
printf("union=");
printf("{");
for (i = 0; i < a; i++) {
for (j = 0, l = 0; j < k; j++) {
if (A[i] != I[j]) // this is A-B
{
l++;
if (l == (k)) {
printf("%d,", A[i]);
}
}
}
}
for (i = 0, k = 0; i < a; i++) {
for (j = 0; j < b; j++) {
if (A[i] == B[j]) {
printf("%d,", A[i]); // intersection
I[k] = A[i];
k++;
}
}
}
for (i = 0; i < b; i++) {
for (j = 0, l = 0; j < k; j++) {
if (B[i] != I[j]) {
l++;
if (l == (k)) {
printf("%d,", B[i]); // this is B-A
}
}
}
}
printf("}\n");
// union calculation ended here
printf("A-B = ");
printf("{");
for (i = 0; i < a; i++) {
for (j = 0, l = 0; j < k; j++) // A-B calculation
{
if (A[i] != I[j]) {
l++;
if (l == (k)) {
printf("%d,", A[i]);
}
}
}
}
printf("}\n");
printf("B-A = "); // Calculates B-A
printf("{");
for (i = 0; i < b; i++) {
for (j = 0, l = 0; j < k; j++) {
if (B[i] != I[j]) {
l++;
if (l == (k)) {
printf("%d,", B[i]);
}
}
}
}
printf("}\n");
return 0;
}
#include <iostream>
using namespace std;
long long int acc = 0;
bool isValid(int x, int y, int m[5][5])
{
if(x > -1 && x < 5 && y > -1 && y < 5 && m[x][y] == 0)
{
return true;
}
else
{
return false;
}
}
void start(int x, int y, int m[5][5],int count)
{
if(isValid(x,y,m))
{
count++;
if(count == 25)
{
acc++;
}
else
{
m[x][y] = 1;
start(x+1,y,m,count);
start(x-1,y,m,count);
start(x,y+1,m,count);
start(x,y-1,m,count);
start(x+1,y+1,m,count);
start(x-1,y-1,m,count);
start(x+1,y-1,m,count);
start(x-1,y+1,m,count);
}
}
}
int main()
{
int map[5][5];
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
map[i][j] = 0;
}
}
start(2,2,map,0);
cout<<acc;
}
or another code which i tried
#include <iostream>
#include <vector>
using namespace std;
long long int acc = 0;
class Point
{
public:
int row;
int column;
int count;
int map[5][5];
};
vector<Point> pts;
bool isValid(Point *b)
{
if(b->column > -1 && b->column <5 && b->row > -1 && b->row < 5 && b->map[b->column][b->row] != 1)
{
return true;
}
else
{
return false;
}
}
void start(vector<Point> A)
{
if(A.size() == 0)
{
cout<<acc;
}
Point *temp = &A.back();
A.pop_back();
if(isValid(temp))
{
temp->map[temp->column][temp->row] = 1;
temp->count = temp->count + 1;
if(temp->count == 25)
{
acc++;
}
else
{
Point *p = new Point;
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
p->map[i][j] = temp->map[i][j];
}
}
p->column = temp->column + 1;
p->row = temp->row;
p->count = temp->count;
A.push_back(*p);
Point *q = new Point;
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
q->map[i][j] = temp->map[i][j];
}
}
q->column = temp->column - 1;
q->row = temp->row;
q->count = temp->count;
A.push_back(*q);
Point *r = new Point;
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
r->map[i][j] = temp->map[i][j];
}
}
r->column = temp->column;
r->row = temp->row + 1;
r->count = temp->count;
A.push_back(*r);
Point *s = new Point;
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
s->map[i][j] = temp->map[i][j];
}
}
s->column = temp->column;
s->row = temp->row - 1;
s->count = temp->count;
A.push_back(*s);
Point *t = new Point;
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
t->map[i][j] = temp->map[i][j];
}
}
t->column = temp->column + 1;
t->row = temp->row + 1;
t->count = temp->count;
A.push_back(*t);
Point *u = new Point;
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
u->map[i][j] = temp->map[i][j];
}
}
u->column = temp->column - 1;
u->row = temp->row - 1;
u->count = temp->count;
A.push_back(*u);
Point *v = new Point;
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
v->map[i][j] = temp->map[i][j];
}
}
v->column = temp->column + 1;
v->row = temp->row - 1;
v->count = temp->count;
A.push_back(*v);
Point *w = new Point;
for(int i = 0; i < 5; i++)
{
for(int j = 0;j < 5; j++)
{
w->map[i][j] = temp->map[i][j];
}
}
w->column = temp->column - 1;
w->row = temp->row + 1;
w->count = temp->count;
A.push_back(*w);
}
}
cout<<A.size();
start(A);
}
int main()
{
pts.clear();
Point *p = new Point;
p->map[2][2] = 0;
p->column = 2;
p->row = 2;
p->count = 0;
cout<<p<<endl;
pts.push_back(*p);
start(pts);
}
the first runs for about 150 iterations and then outputs 0, to indicate no completepaths, which is definitely wrong.
the second seems an error in pointers and addresses, which i still cannot get my head around.
What's wrong with this code? while loop part doesn't work. if statement is not enough to terminate while loop
int main(void) {
int data[SIZE] = { 12,2,5,8,2,45,89,0,12,4 };
int i, j, tmp;
for (i = 0; i < SIZE-1; i++) {
j = i + 1;
tmp = data[j];
while (j > 0){
if(data[j-1] > tmp){
data[j] = data[j - 1];
j--;
}
}
data[j] = tmp;
}
for (i = 0; i < SIZE; i++)
printf("%d, ", data[i]);
return 0;
}
j--; is inside your if statement. If data[j-1] > tmp is false your loop will not terminate. Apart from this your algorithm does not sort the array. Adapt your code like this:
int main (void)
{
int data[SIZE] = { 12,2,5,8,2,45,89,0,12,4 };
int i, j, tmp;
for (i = 0 ; i < SIZE - 1; i++)
{
j = i+1;
while ( j > 0 && data[j] < data[j-1])
{
tmp = data[j];
data[j] = data[j-1];
data[j-1] = tmp;
j--;
}
}
for (i = 0; i < SIZE; i++) {
printf("%d, ", data[i]);
}
return 0;
}